You can now download version 0.8.21 from https://addons.mozilla.org/en-US/firefox/addon/keefox/
This is a required upgrade for all users. You must upgrade before the end of June 2011 or KeeFox will stop working. Firefox should automatically prompt you to install a new version soon and future versions of KeeFox will keep up to date automatically through the official Firefox add-ons site.
Apart from the switch to an automatic update system, there are a few other minor improvements too. Full details are available in the changelog as usual: http://keefox.svn.sourceforge.net/viewvc/keefox/trunk/Firefox%20addon/CHANGELOG.txt